Means for utilizing exhaust steam



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@eto 4l, H9 J. E. JoHANssoN MEANS FOR UTILIZING EXHAUST STEAM Filed NOV.17, 1953 5 Sheets-Sheet l f Vgn @5am/@MM a ATTORNEY @QL 4, 1938., L E,JOHANSSON ZSZHZ MEANS FOR UTILIZING EXHAUST STEAM Filed NOV. 17, 1935 5Sheets-Shes?I 2 Whig 7 65 6g @ffmwi A TORNEY @ct- 49 @3%. J. E.JoHANssoN MEANS FOR'UTILIZING EXHAUST STEAM Filed Nov. 17, 1935 3Sheets-Sheet 5 2 IVENTOR i ATToRN d Patented Cet. 4, 1938 PATENTv OFFICE2,132,212 MEANS FOR UTLLIZING EXHAUST STEAM Johan Erik Johansson,Goteborg, Sweden, as-

signorv to Aktiebolaget Gtaverken, Goteborg, Sweden, a corporation of`Sweden Application November 17, 1933, Serial No. 698,512 In Sweden June5, 1928 4 Claims.

This application is a continuation in part replacing my copendingapplication lSerial No. 383,132, filed August 2, 1929.

The present invention relates to means for utilizing exhaust steam ofreciprocating steam` engines and has for its general object theprovision .of means for transforming the available heat content of theexhaust steam into energy absorbed by the steam during expansion in therem cipro'cating steam engine. More particularly, the

invention relates to steam power plants comprising a reciprocating steamengine, the exhaust steam of which is utilized in a steam turbinedriving one or more pump devices in. order to compress steam expanded inthe reciprocating steam engine to a higher pressure, thus transformingthe outputof the exhaust steam turbine into heat energy absorbed by thesteam in the reciprocating engine.

Still more particularly, the invention aims to provide combinations andarrangements of parts in such a manner that all of the cylinders of thereciprocating steam engine can be driven by superheated or at leastdrier steam than hitherto has been the case.

Another object of this invention is to provide means for increasing thesmallest 'quantity of steam conveyed by the pump device per unit of timein order to obviate a steamflow through the pump device in a directionopposite to the intended one.

A further object of the invention consists in the provision `of a pumpdevice for the purposes set forth above, which under the greatly varyingoperation conditions can be driven with the highest possible efficiency.g

A still further object of the invention is to provide means for bleedingsteam from the reciprocating engine for heat exchanging purposes, saidmeans being arranged so as to conduct, as far as possible, vall moisturefrom the engine to the heat exchanging apparatus.

For a better understanding of the nature of the invention and the mannerin which it is carried into eiect, reference may be had to theaccompanying drawings forming a part of this specication and thefollowing description thereof.

In the drawings:

Fig, l is a plan view, partly in section, showing an embodiment of theinvention;

Fig. 1a is a section taken on the line Ia--Ia of Fig. 1.

Fig, 2 shows an indicator diagram;

Fig. 3 shows a modification of a detail of Fig. 1 in section.

Figs. 4 and 5 are diagrams illustrating the mode of operation of theturbo compressors used in the steam power plant according to theinvention;

Fig. 6 is a modification of the steam power plant illustrated in Fig. 1;,.5 Fig. 'l is a sectional view in an enlarged scale taken on the lineVII--VIIof Fig. 6; and

Figs. 8 and 9 are details of Fig. '7.

Referring now to Fig. 1, reference numeral I indicates a reciprocatingsteam engine arranged for triple expansion of steam in the cylinders 2,3 and 4 thereof, high pressure steam being supplied from the steamgenerator 5 through the conduit 9 to the main stop valve 'I and,therefrom, to the piston valve 8. After expansion in the high pressurecylinder 2 the steam passes through the pipe 9, which serves as areceiver, into the distributing valve chest II) and to the piston valveII and, therefrom, into the intermediate pressure cylinder 3. Afterhaving expanded therein, the steam is exhausted into the receiver I2 andthen enters, by means of the slide valve I3, the low pressure cylinder 4which exhausts the steam expanded therein into the exhaust steam pipe I4connected with the condenser I5. The pipe I4 is further connected bymeans of a pipe I6 with an exhaust steam turbine Il driven by steamnally expanded in the reciprocating engine I. After having expanded inthe exhaust turbine I'I, the steam flows through a conduit I8 into thecondenser I5.

The steam turbine II drives by means of a shaft 92, a low pressure turbocompressor vI9 rotating at the same speed as the turbine. A gearing 2Uconnected with the turbine drives, by 3 means of a shaft 93 partly lyingbelow the shaft 92, a reciprocating high pressure compressor 2l. Theexhaust steam pipe I4 is also connected with a pipe 22 conducting steamto the suction side of the compressor I9. Stop valves 23, 24, and 25 arearranged in the pipes I4,l I6, and 22, respectively. A container 26located in the pipe 2.2 serves to equalize the diierence between thequantity of steam flowing into the pipe 22 and the quantity of steamsucked in by the compressor I9 per unitof time.' The pressure side ofthe compressor I9 is connected, by means of a pipe 2l, with the receiverI2 at a point .adjacent the slide valve I3. A pipe 28 connects thereceiver I2 with the suction side of the compressor ZI. The pressurepipe 29 of this compressor is connected with a superheater 39 arrangedin the flue passage 3I of the boiler 5 and, by means of pipe 32, withthe receiver pipe 9 at a point adjacent the piston valve I I. A by-passpipe 44 havingv a 55 throttle valve 45 connects the pressure side of theturbocompressor with its suction side.

During normal operation, the stop valve 23 is in closed position whereasthe valves 24 and 25 are opened so as to allow flow of steam from theexhaust pipe I4 to the steam turbine I"I and to the compressor I9. Thesteam sucked in by the compressor I9 is compressed to a pressure whichis substantially equal to the pressure prevailing in the receiver I2,whereupon this steam, which has been superheated or at least dried bycompression, is conducted through the pipe 21 to the said receiver forfurther expansion in the low pressure cylinder 4. It is obvious that themixture of steam entering the low pressure cylinder will have a highertemperature or be drier than the steam exhausting from the intermediatepressure cylinder. low pressure cylinder will be increased materiallyand the low pressure cylinder will be fed with superheated or dry steam.In this manner, a portion of the output of the exhaust steam is renderedserviceable for the low pressure cylinder in the form or" an increasedquantity of steam of a higher temperature or at least having lessmoisture and a pressure suitable for utilization in this cylinder. Thereceivers 9 and I2 communicate in a similar manner with the highpressure compressor 2l by means of the conduits 28, 29, and 32. Thesteam taken out from the receiver I2 is compressed by the reciprocatingcompressor 2| to a pressure which is substantially equal to the pressureVprevailing in the receiver 9. 'Ihe compressed steam which has beensuperheated by compression is still more superheated in the superheater3B.

As will be seen from the drawings, the steam which has been compressedby the high pressure compressor is conducted back to the reciprocatingengine at a point situated behind the high pressure cylinder, since thecompression of steam up to the pressure prevailing in the live steampipe would cause considerable diiculties. Therefore, I prefer tocompress the steam to a pressure not higher than the pressure prevailingin the irst receiver.

If it is desired to disconnect the turbine and the compressors, this maybe eiected by conducting the steam through the exhaust pipe I4 directlyinto the condenser I5. For this purpose, the valve 23 is opened and thevalves 24 and 25 are closed.

In Fig. 1, I have also shown means for bleeding steam from thereciprocating steam engine, this steam being used for preheating of feedwater. For this purpose, three feed water preheaters 33, 34, and 35 areconnected to the reciprocating steam engine by means of pipes 36, 31 and38 respectively. 'Ihe feed Water passes from the condenser I5 throughthe pipe 39 and the preheaters to the pump device 40 and, therefrom,into the boiler 5. 'I'he feed Water preheater 33 is connected with theexhaust side of the valve chest of the low pressure cylinder so that aportion of the steam finally exhausted in the reciprocating engine isconducted to this preheater. The next preheater 34 is connected with thereceiver I2. As the pressure side of the compressor I9 is connected withthe same receiver, I have chosen such an arrangement of the pipes 21 and31 that steam compressed by the compressor I9 is conducted into thereceiver I2 at a point adjacent the slide valve I3 whereas the steam tobe tapped off from this receiver is taken out at a point adjacent thepiston valve II. Because of the arrangement Thus, the output of the thusprovided superheated steam delivered from the compressor will tend toflow in a relatively short and direct path to the slide valve I3,whereas the preheater 34, the inlet of which is adjacent the valve II,will tend to draw oi the relatively low quality steam discharged fromthe latter valve. With the arrangement illustrated, the natural path offlow of steam admitted to the receiver I2 from valve II and from thecompressor discharge conduit 21 will tend to maintain a substantiallyhigher quality of steam into the zone adjacent to the valve I3 than inthe Zone adjacent the inlet to the preheater. Consequently, the hightemperature steam delivered from the compressor is substantiallyutilized in the succeeding cylinder of the engine and preheating isaccomplished by steam of relatively low quality as exhausted to thereceiver.

Itis further to be noted that in view of the general flow of the steamthrough the receiver from the valve II toward the valve I3, the relativepositions of the inlet end of conduit 28 and the outlet end of conduit 2leads to a natural tendency for conduit 28 to withdraw steam of lowerrather than of higher quality from the receiver. If this latter steamcontains moisture, such moisture will, as far as possible, be drawn oiby the pipe 31. In the same manner, the steam compressed by the highpressure compressor 2l enters the receiver 9 at a point adjacent thepiston valve II, Whereas the pipe 38 is connected with the receiver 9 ata point adjacent the outlet of the high pressure cylinder 2.

In order to reduce the dimensions of the compressors and the work ofcompression, the pressure of the steam supplied to the compressorsshould, if possible, be higher than the pressure prevailing in thecylinders during the exhaust period. This may be effected if the steamof a higher pressure exhausted from the cylinders during the exhaustlead period is supplied to the compressors, While the steam exhaustedduring the exhaust period is utilizedv for further expansion in thefollowing cylinder or in the exhaust turbine respectively. Therefore, ifaccordatthe point 4I, an increased average pressure of the steamsupplied to the compressor may be obtained.

Y For this purpose, the stop valve 25 inthe conduit 22 may be replacedby a non-return valve opening in the direction to the suction side ofthe compressor. Fig. 3 shows this modified arrangement. As the steamquantity entering the pipe I4 during the exhaust lead period of the loWpressure cylinder is materially greater than the steam quantityenteringsimultaneously the steam turbine I1, the pressure in the conduit I4 willincrease. The non-return valve 42 then opens and the greatest portion ofthe steam exhausted during the exhaust lead period flows into thecontainer 26. As during the exhaust period the pressure decreases in theconduit I4, the non-return valve closes and prevents the steam of higherpressure from ilowing back to the conduit I4. The steam exhausted duringthe exhaust period will then flow to the steam turbine I1.

On account of the great variations of the oW of steam through thecylinders of the reciprocating steam engine and the great changes in thesteam quantities conveyed to the compressors,

til() pr-.essor per unit of time.

the compressors will Work A.under peculiar operating-conditions. I vhavefound that, if the turbo compressor is constructed in the ordinarymanner so as to normally give its maximum efliciency with the steamquantity conveyed per unit 4of time, the efficiency obtained willactually be considerably lower. I therefore, construct the turbocompressor so that its maximum efficiency occurs with a 'quantity'ofsteam exceeding the average quantity conveyed per unit of time by atleast 25 per cent. The operating conditions of the turbo compressor willbe described more particularly in connection with Figs. 4 and 5.

f Referring to Fig. 5, V represents the volume which, zat .a certain`crank position of the reciproeating steam engine, flows through thecom- The line 46 indicates the changes in volume during one crankrevolution and the line 41 represents the average volume Vm conveyedduring said period. In the corresponding diagram in Fig. 4, theabscissae of the coordinate system represent the volume conveyed to thecompressor andthe ordinates thereof represent the efliciency of thecompressor. Curve 48 indicates the changes of the pressure efficiency nwith the volume V with a compressor intended to give its maximumeiliciency at the average volume Vm, While vcurve 49 indicates thechanges of the efriciency of a `compressor which gives its maximum-eiiiciency at a volume of 1.5 Vm. Ina compressor loperating .with thechanges of volume indicated by curve 46 and having an eiciency curveaccording to 48, `an average eiciency is obtained which'corresponds tothe distance 5I indicated in the diag-ram, whereas the averageefliciency of a compressor with an efficiency curve according to 49reaches a considerably higher value represented by the distance 52. Theupper ends of these two distances 5I and 52 are situated on a curve 5l)on which a plurality of points may be calculated for compressors withother efficiency curves. After such Va curve 5l] has been plotted itwill .be possible to determine the average efliciency 11m under theconditions indicated for a compressor which is dimensioned so as to haveits maximum efficiency at the volume correspond- 'ing vto the point ofthe curve where the average efficiency is read off.

`The curves 48 land 43,'and corresponding curves for other volumes, haveybeen obtained by tests with turbo compressors, and for the determina-.tionof curve .50 the following equation has been Iused.:

EV'v] Vmzf where t represents the time during which .the volume V iiowsthrough the compressor. i If 2t represents the time of one revolution ofthe reciprocating steam engine, this expression can be replaced by 360,t being measured in degrees on the `diagram in Fig. 5. For thecalculation of 11m for a compressor having an efciency curve according:to curve 48, for example, the volume V is measured for a certain smallangular displacement t" v.on the diagram in Fig. 5. With .the valueofV'thus obtained the value of the corresponding n is `measured Von thecurve 48. After the wholediagrarn'li has been vmeasured in this mannerand multiplied by the corresponding q-values, EVqcan -be obtained andthus also EVr] Vm 36o llherehyapointshas been .deter-mined .on curve 50.

By a similar calculation for a plurality of other efciency curves thedetermination of curve 5D has been effected;

It will .appear from the form of this curve that it has its lowest valueat small volumes, and that it reaches a'maximum value at a Volume ofabout 1.5 Vm, whereupon it slowly falls with greater V-values.Consequently, the compressor should .be so constructed as to have itsmaximum efficiency at a volume of 1.5 Vm, it being possible, however, topermit variations of this Volume between the limit values 1.25 Vm and2.5 Vm Without :the average efficiency being materially lowered. By anoverdimensioning of the compressor,

which may be effected, for instance, by increasing the width ofthechannel areas of common turbo compressors, the Iadditional advantage isobtained that the friction losses during the flow of steam through thecompressor are reduced.

In Fig. 4 also a curve 53 has been shown, which indicates thepressure-increasing ability of the turbo-compressor at different valuesof the steam volume conveyed. It will be seenfrom the diagram that thepressures are remarkably low at small steam volumes, that is to say forthe extent Ikof lthe `diagram denoted by 54-55. This circumstance isexplained by the fact that av per-iodic flow of steam `takes placethrough the com- .pressor in a direction opposite to the intended onefor said portion of the diagram. As the .energy .transferred by thecompressor to the steam is lsubstantially constant, the main portion ofthe energy is under such circumstances transformed into an increase `intemperature of the steam. An increase in pressure as far vas possiblewould be, however, more `desi=rablesince this latter form .of energy iseasier to transform, by means of the reciprocating steam engine, intomechanical work. To ensure -such an increase of the pressure, the

.turbo compressor t9 is by-passed Lby pipe -44 in which is inserted athrottle valve 45. By means of pipe 44 a portion of steam .which hasalready :been compressed is returned to the suction side of vthecompressor, in order thus to prevent the entrance :of too .small -steamVolumes conveyed by the compressor per unit of time. In Fig. 5, thevdiagram 'designated `by 46 shows the variations of the IvolumeAconveyed by the compressor per vunit of time if :there is no return ofsteam from the pressure side to the `suction side thereof, and thecombination with curve 53 on Fig. 4 makes it iclear that the pressurescorresponding .to the smallest volumes will fall on the portion of thepressure curve 53 extending between the points 54and :55.

In consequence of the steam quantity which vreturns through the `by-passpipe 44 to the suction side of the compressor, :a steam quantitycorresponding to curve 56 indicated -in Fig. 5 Aby chaindotted lineswill then flow through the compressor, so that all volumesycorresponding to the portion 54-55 willfbe avoided. With thearrangement .-set forth, the compression in the comvpressor'may thus 'becaused to develop exclusively according 4to the portionon the right ofpoint 55 of the pressure curve .53 shown in Fig. 4, the best economicalresult being thus obtained, in that the `energy supplied by thecompressor is transformed as far as possible into an increase of thepressure of the steam. l

In the modification shown in Figs. `6 to -9, the live Asteam enters `thedistributing valve chest 51 zand, .after .having 'expanded in the highpressure cylinder 2, enters the vreceiver :58. The steam .then `ovvsthrough the intermediate and .low

pressure cylinders 3 and 4, respectively, into the exhaust steam pipeI4, as described in connection with Fig. 1. The piston valve II of theintermediate pressure cylinder and the slide valve I3 of the lowpressure cylinder are connected by means of a pipe 59 which serves as apart of the low pressure receiver I2. The exhaust steam turbine I1drives two turbo compressors I9 and 60, respectively. 'I'he suction sideof the low pressure compressor is connected to pipe 22 and its pressureside is connected, by means of pipe 21, with the low pressure receiver59, I2. By means ol the pipe 28, the high pressure cornpressor 50 sucksin steam from the receiver 59, and the co-mpressed steam is conductedthrough pipe 29, superheater 30, and pipe 32 into the receiver 58 at apoint adjacent the piston valve II of the intermediate pressure cylinder3. The pipe 31 for bleeding steam from the low pressure receiver isconnected to pipe 59 at a point adjacent the steam outlet chamber 6I ofthe intermediate pressure cylinder, while the pipe 38 through whichsteam of higher pressure is bled, is connected with the outlet chamber62 of the high pressure cylinder. Y

Allof the parts indicated in Figs. 6 and '7 by the same referencenumerals as in Figs. 1 and 3 serve the same purpose and operate in thesame manner as the corresponding parts of Figs. 1 and 3.

While the low pressure compressor I9 is bypassed by a pipe 44 with athrottle valve 45 in the same manner and for the same purpose as in Fig.l the high pressure compressor 69 is bypassed by a pipe 63 connectingthe receiver 58 with the receiver 59. The connecting pipe 63 is providedwith a stop valve 64 and with a controlling device 65 which is shown ona larger scale in Fig. 9. The controlling device 65 comprises a cylinder66 and a double piston 61 rigidly connected with the piston valve I I.The upper part of piston 61 and the cylinder 66 are provided withapertures 68 and 69, respectively, these apertures controlling the ilowof steam from the receiver 58 through the pipe- 63 to the receiver 59,depending on the position of the double piston 61 during each revolutionof the reciprocating engine; The two parts of the double piston and theapertures are situated relatively to each other in such a manner that aflow of steam through pipe 63 is possible only during those periods inthe engine cycle when the steam quantity conveyed by the turbocompressor 60 tends to fall below the value indicated by the point 55 inthe diagram of Fig. 4. During such periods the controlling device 65 isopened by movement of the piston valve I I so that, during theseperiods, a steam quantity according to the curves 10 in Fig. 5 will flowthrough the compressor 60 in order to prevent the entrance of too smallvolumes conveyed by the compressor per unit of time. The arrangement ofthe controlling device is somewhat more complicated than the singlethrottling valve 45, but offers, on the other hand, the advantage thatan increase of the steam volume conveyed by the compressor takes placeonly during two short periods of each revolution of the reciprocatingsteam engine, thus decreasing the necessary amount of work required bythe compressor.

In the modification according to Figs. 6 to 8, I have also shown anarrangement adapted to draw off steam from the low pressure cylinder 4to the low pressure compressor I9 during the expansion in the cylinder,an exhausting means being controlled so as to open at a point 43 (Fig.

2) before the beginning of the exhaust lead period representedat 4|,whereby steam of a higher pressure is supplied to the suction conduit ofthe compressor. In this case, the pressure curve will sink somewhat asindicated in Fig. 2 f

by dash lines.

To effect this mode of operation, the cylinder covers 1I and 12 of thelow pressure cylinder are provided with valves 13 and 14, respectively,connected with pipes 15 and 16, respectively, which supply the steamdrawn off from the cylinder to the container 26 and the compressor I9.The pipes 15 and 16 may be connected by a pipe 94. Under the influenceof springs 11 and 18, the valves 13 and 14 are normally kept in closedposition. .The valve 13 is actuated by means of a lever 19 which isconnected with a rod 80 guided by a bracket BI. The lower end of the rod88 is provided with a roll 82 cooperating with a cam wheel 88. A spring84 prevents disengagement of the roll 82 and the cam wheel 83. The camwheel is keyed on the crank shaft 85 and has an outwardly projecting cam86 and, o-n the opposite side, a recess 81.

When the cam wheel is turned from the position shown in Fig. 8 in acounter-clockwise direction, the cam 86 will cause an upward movement ofthe rod 80 and a movement of the lever 19 about its iulcrum 88 in aclockwise direction, whereby the valve 13 is opened against theresistance of the spring 11. The cam 86 has such a position relativelyto the crank 89 of the low pressure cylinder that the valve 13 begins toopen at a point of the steam process corresponding to the point 43 inFig. 2. The valve 14 on the other cylinder cover is actuated in asimilar manner by means of the lever 90 likewise connected with the rod88. When the recess 81 of the cam wheel is in a position below the roll82, the rod 80 will be moved downwardly and the lever 90 turned in acounter-clockwise direction, thus opening the valve 15 against theresistance of the spring 18. By means of a hand lever 9|, the cam wheel83 is movable to a position indicated by 92, the valves 13 and 14 thenbeing out of operation.

While in the foregoing description I have confined my consideration toa. steam power plant comprising a triple expansion steam engine and twocompressors, it will be understood that the invention is not confinedtof this specific arrangement but may equally well be embodied in steampower plants in which two or more cylinders are employed for expandingthe steam down Afrom boiler pressure to exhaust pressure and only onecompressor is provided for the compression of steam. f

what 1 Claim iszl. In a steam power plant, a reciprocating steam enginehaving a plurality of cylinders for multiple stage expansion of steam inthe engine, said cylinders being double acting and the opposed ends ofthe same cylinder operating to expand steam through the same pressurerange, means for admitting steam to and exhausting steam from each ofsaid cylinders, a compressor, a turbine for driving said compressor, aconduit for conducting steam exhausted from one of said cylinders to thesuction side of said compressor and a second conduit for conductingcompressed steam from said compressor back to said engine forreexpansion therein, said compressor being constructed to operate withmaximum efliciency when steam is supplied thereto at a rate equal to atleast one and one-quarter times but not exceeding two and one-half timesthe average rate at which steam is delivered by the engine.

2. In a steam power plant, a reciprocating engine having a plurality ofcylinders for multiple stage expansion of steam in the engine, saidcylinders being double acting and the opposed ends of the same cylinderoperating to expand steam through the same pressure range, means foradmitting steam to and exhausting steam from each of said cylinders, anexhaust steam turbine for expanding exhaust steam from said engine to apressure lower than that to Which the steam canl be expanded in theengine, a compressor driven by said turbine, a conduit for conductingsteam exhausted from one of said cylinders to the suction -side of saidcompressor and a second conduit for conducting compressed steam fromsaid compressor back to said engine for reexpansion therein, saidcompressor being constructed to operate with maximum eiciency whenste-am is supplied thereto at a rate equal to at least one andone-quarter times but not exceeding two and one-half times the averagerate at Which steam is delivered by the engine.

3. In a steam power plant, a reciprocating engine having a plurality ofcylinders for serial second conduit connecting said one of saidcylinders with the suction side of said pumping means, valve means forcontrolling iiow of steam through said second'conduit, said valve meansbeing opened and closed in accordance with the position of the crankshaft of said engine to permit steam to flow through said second conduitduring a predetermined period of the engine cycle, and a third conduitfor returning the steam delivered from said pumping means to said engine.for further expansion therein.

4. In a steam power plant, a reciprocating engine having, a plurality ofcylinders for serial expansion of steam therein, means for admittingsteam to and exhausting steam from each of said cylinders, a steamturbine, a conduit for conducting exhaust steam from said engine to saidturbine, pumping means driven by said turbine, a second conduit for'conducting exhaust steam from said engine to the suction side of saidpumping means, a third conduit connecting the low pressure cylinder ofsaid engine with the suction side of said pumping means, valve means forcontrolling flow of steam through said third conduit, said valve meansbeing opened and closed in accordance with the position of the crankshaft of said engine to permit steam to fioW through said third conduitduring a predetermined period of the engine cycle, and a fourth conduitfor returning steam delivered by said pumping means tosaid engine forfurther expansion therein.

JOHAN ERIK JOI-IANSSON.

